ARM processors were originally designed and optimized for low power consumption applications. The emphasis on power efficiency makes ARM processors well-suited for use in mobile and embedded devices where battery life is a critical factor.
History and Origins of ARM
ARM stands for Advanced RISC Machines. ARM began as a joint venture between Acorn Computers, Apple Computer, and VLSI Technology in the 1980s. Acorn was interested in developing a low-power processor for its personal computers. Inspired by academic research papers on RISC (Reduced Instruction Set Computing), Acorn decided to design its own RISC processor rather than license an existing complex instruction set computing (CISC) design.
The first ARM processor was the ARM1, launched in 1985. It used a 32-bit RISC architecture with a lean set of instructions that could be executed efficiently in a single clock cycle. This improved performance while reducing power consumption compared to CISC chips at the time. The ARM2 followed in 1987, further enhancing the design.
In 1990, Acorn spun off ARM into its own company. ARM focused on licensing its RISC processors to other companies rather than manufacturing its own chips. This licensing model allowed ARM’s architecture to become widespread in the embedded electronics industry.
Power Efficiency
ARM’s RISC architecture was designed from the ground up to be power efficient. Some of the key attributes that contribute to this efficiency include:
- Small and simple instruction set – RISC instructions operate on register operands rather than directly accessing memory, simplifying the design of the processor and reducing power needs.
- Load/store architecture – Data operations only occur between registers and memory through explicit load and store instructions. This simplifies instruction decoding and pipelining.
- Fixed length 32-bit instruction format – Having all instructions at 32 bits simplifies fetching and decoding.
- Few addressing modes – Most ARM instructions just use 2-3 operand addressing modes, avoiding complex memory accesses.
- Pipelined execution – Overlapping fetch, decode, execute stages improves efficiency.
- Extensive clock gating – Unused parts of the chip can be powered down when not needed.
In addition, ARM implements other advanced techniques like dynamic voltage and frequency scaling, throttling, and power gating to minimize power draw. The ARM architecture is streamlined to accomplish tasks with as little power as possible.
Embedded Systems
The emphasis on power efficiency made ARM processors perfectly suited for small, low power embedded systems. Some examples of embedded systems that leverage ARM processors include:
- Mobile phones and smartphones
- Tablets and mobile computing devices
- Digital cameras and video recorders
- Portable gaming systems
- Smart watches and wearables
- MP3 players
- GPS navigation and tracking devices
- Networking equipment like routers, switches, etc.
- IoT and edge devices like smart home tech, sensors, etc.
- Microcontrollers in appliances, toys, vehicles, and industrial systems
ARM’s licensing model allowed their RISC architecture to be adapted into a wide range of custom system-on-chip (SoC) designs for low-power embedded applications. ARM cores could be integrated with peripherals, memory, and custom logic suited for a specific device’s needs. Even low-cost microcontrollers can leverage ARM’s efficiency and performance.
As portable electronics and IoT devices have grown exponentially, ARM established a commanding position as the most popular choice for embedded 32-bit processors. Over 100 billion ARM chips have shipped to date for embedded systems.
Mobile Computing
ARM processors enabled the mobile computing revolution. As personal digital assistants (PDAs) evolved into smartphones in the 2000s, ARM cores provided the power efficiency to enable all-day battery life in these devices.
Early mobile devices like the Apple Newton and PalmPilot used low-power ARM processors. As mobile phones gained capabilities like networking, cameras, touch displays, and apps, more advanced ARM application processors and systems-on-chip were developed. Companies like Qualcomm, Apple, Samsung, and others worked with ARM to optimize their designs for mobile.
Performance, power, cost, and thermal considerations make ARM the preferred architecture for mobile applications. ARM cores scale from ultra low-power Cortex-M microcontrollers to high-performance Cortex-A series suitable for demanding apps. Advanced big.LITTLE designs couple energy-efficient LITTLE cores with high power big cores.
Today’s smartphones, tablets, and other mobile devices have advanced capabilities rivaling laptop computers while maintaining all-day battery life. ARM deserves much credit for making this possible and enabling the mobile revolution.
Servers and Supercomputers
While ARM has dominated the mobile space, they have also made moves into the server and high performance computing markets. Once again, the focus on power efficiency provides benefits.
Modern data centers face challenging power and cooling demands. ARM-based server CPU designs promise significantly better energy efficiency for cloud workloads. ARM processors may also have advantages in performance per dollar and performance per watt.
Major companies like Amazon Web Services, Microsoft, and Qualcomm have invested in developing ARM server platforms. Rackspace and packet.com offer ARM cloud hosting options. ARM chips show promise for web serving, big data, machine learning, and other cloud workloads.
On the supercomputing side, Japan’s Post-K exascale supercomputer and Fujitsu’s Fugaku ARM-based supercomputer top global performance rankings. HPC sites appreciate ARM’s power efficiency and cost savings for massively parallel workloads.
While still a small part of the server and HPC ecosystem today, ARM is disrupting the Intel x86 dominance in this space with its energy and cost benefits. This beachhead may grow significantly in coming years.
Security
Security is an increasingly important requirement for many embedded and mobile devices today. Features like touch ID fingerprint authentication, Apple Pay, DRM protected media, and access to confidential data heighten security needs.
ARM takes security seriously with features like TrustZone, a system-wide approach to security on ARM-based systems. It provides hardware isolation of secure and normal worlds to protect sensitive data and trusted apps. Cryptography accelerators and security extensions are also available.
Because of their role in so many consumer and business devices, ARM recognizes that strong security is crucial for user trust. Addressing security concerns was a major factor underlying ARM’s architectural design principles and developments.
Conclusion
To summarize, ARM processors were originally designed for efficiency in order to enable low power embedded applications. The emphasis on power savings, compact architectural simplicity, and custom system-on-chip implementations has made ARM the premier choice for mobile computing and embedded devices. ARM’s licensing model caused their architecture to spread widely across the electronics industry. While they rose to prominence in mobile and embedded roles, ARM processors are now expanding into servers, supercomputing, networking, automotive, and other areas. With over 100 billion chips shipped, ARM’s focus on power efficiency has fueled their dominance across multiple domains.
